We will recruit, screen, and enroll 50 HIV-seropositive individuals into an outpatient, prospective, stratified, randomized, double-blind, multi-site phase II trail of Peptide T vs. placebo. Patients will have moderate cognitive deficiency and CD4 cell count less than 500. Phase I studies suggested a possible beneficial effect of peptide T on certain cognitive processes in HIV patients, raising the possibility that it may potentially reverse existing moderate to severe cognitive impairments that often accompany HIV infection.